100 Important Scientific Reasons Page 2 of 4

100 Important Scientific Reasons Page 2 of 4

26) Polar star is always seen in the north.

Ans: It is because the Polar Star (North Star) is closest to the location of the celestial North Pole.

27) We never see birds urinating.

Ans: The birds do not have a urinary system like other living beings which possess urinary excretory organs. In the birds the urine is excreted from body without special organs.

28) Pasteurized milk has more nourishment than the ordinary boiled milk.

Ans: Pasteurized milk is obtained by heating milk at a temperature of 60 degree Celsius for 30 minutes. In this way the TB bacteria are killed without damaging the milk protein. Thus pasteurized milk has more nourishment than ordinary boiled milk.

29) Bees die when they sting human being.

Ans: Their stingers are actually ovipositors, tubular structures extending from the abdomen that sometimes contain eggs. When the barbed stinger is left inside the victim, the honeybee mortally tears her abdomen in the process. They leave their stingers in the wound with a tiny venom sac attached. Fortunately, only about one out of a hundred people are allergic to bee sting, but allergic reactions can be very serious.

30) Cloudy nights are usually warmer than the clear ones.

Ans: The clouds serve as a barrier and prevent the loss of heat. Thus the warm temperature is maintained.

31) Why do some people snore?

Ans: Some people snore during their sleep because the breathing action produces sound. This is so because the pharynx or the windpipe offers resistance to the air taken in or expelled.

32) Why do we sometimes sleep walk?

Ans: Sleep walk is a sort of disorder of sleep in which a person starts walking during his sleep.

The sleeper walks and performs complex activities automatically without regaining consciousness.

33) Climbers bend forward while climbing mountain.

Ans: While climbing a mountain, a climber bends his body forward in order to keep the centre of gravity of his body within two thirds portion. According to this principle the Pisa Tower is not falling.

34) Why climbers get their food by climbing on other trees?

Ans: The climbers are mostly parasites and they cannot manufacture their food. Therefore, they climb on other trees and get food from them.

35) Mars is called red planet.

Ans: Mars is called the red planet because its colour is red due to the desert like surface.

36) Vitamin D is the essential component of the body.

Ans: Vitamin D is necessary for body because it is essential for bone formation and retention of calcium in the human body. Vitamin D also protects the teeth.

37) The weight of the object is less at the equator than at the poles.

Ans: The weight of an object is the product of mass and force of gravity. The equatorial diameter is more than the polar diameter. Thus, the force of gravity is more at the poles and the weight is more there.

38) The dogs pant, the birds open their mouth and the elephants move rapidly their ears.

Ans: All of them do not sweat; they use the above mentioned mechanisms to cool themselves.

39) A geostationary satellite appears standstill to a viewer on the equator of earth.

Ans: Because the distance remains the same.

40) Why do the stars twinkle?

Ans: The light from the stars travels through different layers of space of varying densities. Therefore, the light rays deviate from their original path. Further, these layers are not stationary but keep on moving. This leads to the twinkling of stars.

41) On what days do we have equal days and nights all over the world? And why?

Ans: On 23 September and 21 March we have equal days and nights all over the world. This is so because on these days, the rays of the sun fall vertically on the equator at noon. Both the poles receive equal rays of the sun. As a result, exactly one-half of each hemisphere receives the sun’s rays. This makes day and night equal.

42) Every fourth year has 366 days. Explain.

Ans: One revolution of the earth around the sun takes 356 days and 6 hours. But we consider a year as consisting of only 365 days and ignore 6 hours. In four years the difference becomes as much as 24 hours or one day. Hence, to every fourth year we add one day. That year of 366 days is known as leap year.

43) Why are igneous rocks called primary or parent rocks?

Ans: Igneous rocks are formed when the molten material from volcanoes gets solidified. This material is liquid, hot and sticky which moves towards the surface through cracks and joints. All other rocks derived from these rocks. Hence, they are called primary or parent rocks.

44) Why are the areas lying between the Arctic Circle and the North Pole in the Northern  Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere very cold?

Ans: These areas are very cold because the sun does not rise much above the horizon. Therefore, its rays are always very slanting which emit minimum heat. These areas being very cold are called Frigid Zones.

45) Why are the three hot regions of the world-equatorial forests, savannah lands and hot deserts-not found in Europe?

Ans: The three hot regions of the world-equatorial forests, savannah lands and hot deserts-are not found in Europe because Europe is the only inhabited continent situated entirely outside the tropics.

46) Why is the lowest layer of the atmosphere in contact with the earth’s surface, the warmest?

Ans: The lowest layer of the atmosphere in contact with the earth’s surface is the warmest because the atmosphere is heated mainly from the below.

47) Why does the temperature above the ocean and land masses vary even on the same latitude?

Ans: Temperature above the oceans and land masses varies even on the same latitude because of the differential heating of land and water, i.e., land mass is heated and cooled more rapidly and to a greater degree than water.

48) Why are marine animals able to live at great depths than marine plants?

Ans: As marine animals do not depend upon sunlight for their survival, they are able to live at great depths where there is permanent darkness.

49) Why do trees of coniferous forests possess needle-like leaves?

Ans: The needle-like leaves limit transpiration and thus enable conifers to grow in the drier areas. 

50) The image of a tree is inverted on the bank of a lake.

Ans: The water of lake acts as a mirror. According to the laws of light, mirror forms inverted images.